linux-kernel - Re: [PATCH v6 04/11] cpufreq/schedutil: use rt utilization tracking

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Message-ID: <20180622135202.GD2512@hirez.programming.kicks-ass.net>
Date:   Fri, 22 Jun 2018 15:52:02 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Vincent Guittot <vincent.guittot@...aro.org>
Cc:     Quentin Perret <quentin.perret@....com>,
        Ingo Molnar <mingo@...nel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Juri Lelli <juri.lelli@...hat.com>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Morten Rasmussen <Morten.Rasmussen@....com>,
        viresh kumar <viresh.kumar@...aro.org>,
        Valentin Schneider <valentin.schneider@....com>,
        Patrick Bellasi <patrick.bellasi@....com>,
        Joel Fernandes <joel@...lfernandes.org>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Ingo Molnar <mingo@...hat.com>
Subject: Re: [PATCH v6 04/11] cpufreq/schedutil: use rt utilization tracking

On Fri, Jun 22, 2018 at 03:26:24PM +0200, Peter Zijlstra wrote:
> > But this also means that we will start to inflate the utilization to
> > get higher OPP even if there is idle time and lost the interest of
> > using dl bw
> 
> You get _some_ inflation, but only if there is actual cfs utilization to
> begin with.

Note that at high idle time, the inflation really is minimal:

f(.2,.2,2)
.20312500000000000000